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Commensal bacterial endocytosis in epithelial cells is dependent on myosin light chain kinase-activated brush border fanning by interferon-?.

ABSTRACT: Abnormal bacterial adherence and internalization in enterocytes have been documented in Crohn disease, celiac disease, surgical stress, and intestinal obstruction and are associated with low-level interferon (IFN)-? production. How commensals gain access to epithelial soma through densely packed microvilli rooted on the terminal web (TW) remains unclear. We investigated molecular and ultrastructural mechanisms of bacterial endocytosis, focusing on regulatory roles of IFN-? and myosin light chain kinase (MLCK) in TW myosin phosphorylation and brush border fanning. Mouse intestines were sham operated on or obstructed for 6 hours by loop ligation with intraluminally administered ML-7 (a MLCK inhibitor) or Y27632 (a Rho-associated kinase inhibitor). After intestinal obstruction, epithelial endocytosis and extraintestinal translocation of bacteria were observed in the absence of tight junctional damage. Enhanced TW myosin light chain phosphorylation, arc formation, and brush border fanning coincided with intermicrovillous bacterial penetration, which were inhibited by ML-7 and neutralizing anti-IFN-? but not Y27632. The phenomena were not seen in mice genetically deficient for long MLCK-210 or IFN-?. Stimulation of human Caco-2BBe cells with IFN-? caused MLCK-dependent TW arc formation and brush border fanning, which preceded caveolin-mediated bacterial internalization through cholesterol-rich lipid rafts. In conclusion, epithelial MLCK-activated brush border fanning by IFN-? promotes adherence and internalization of normally noninvasive enteric bacteria. Transcytotic commensal penetration may contribute to initiation or relapse of chronic inflammation.

SUBMITTER: Wu LL

PROVIDER: S-EPMC4188866 | biostudies-literature | 2014 Aug

REPOSITORIES: biostudies-literature

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Commensal bacterial endocytosis in epithelial cells is dependent on myosin light chain kinase-activated brush border fanning by interferon-γ.

Wu Li-Ling LL Peng Wei-Hao WH Kuo Wei-Ting WT Huang Ching-Ying CY Ni Yen-Hsuan YH Lu Kuo-Shyan KS Turner Jerrold R JR Yu Linda C H LC

The American journal of pathology 20140607 8

Abnormal bacterial adherence and internalization in enterocytes have been documented in Crohn disease, celiac disease, surgical stress, and intestinal obstruction and are associated with low-level interferon (IFN)-γ production. How commensals gain access to epithelial soma through densely packed microvilli rooted on the terminal web (TW) remains unclear. We investigated molecular and ultrastructural mechanisms of bacterial endocytosis, focusing on regulatory roles of IFN-γ and myosin light chain ...[more]

PMID: 24911373

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Project description:Intestinal enterocytes have an elaborate apical membrane of actin-rich protrusions known as microvilli. The organization of microvilli is orchestrated by the intermicrovillar adhesion complex (IMAC), which connects the distal tips of adjacent microvilli. The IMAC is composed of CDHR2 and CDHR5 as well as the scaffolding proteins USH1C, ANKS4B, and Myosin 7b (MYO7B). To create an IMAC, cells must transport the proteins to the apical membrane. Myosin 5b (MYO5B) is a molecular motor that traffics ion transporters to the apical membrane of enterocytes, and we hypothesized that MYO5B may also be responsible for the localization of IMAC proteins. To address this question, we used two different mouse models: 1) neonatal germline MYO5B knockout (MYO5B KO) mice and 2) adult intestinal-specific tamoxifen-inducible VillinCreERT2;MYO5Bflox/flox mice. In control mice, immunostaining revealed that CDHR2, CDHR5, USH1C, and MYO7B were highly enriched at the tips of the microvilli. In contrast, neonatal germline and adult MYO5B-deficient mice showed loss of apical CDHR2, CDHR5, and MYO7B in the brush border and accumulation in a subapical compartment. Colocalization analysis revealed decreased Mander's coefficients in adult inducible MYO5B-deficient mice compared with control mice for CDHR2, CDHR5, USH1C, and MYO7B. Scanning electron microscopy images further demonstrated aberrant microvilli packing in adult inducible MYO5B-deficient mouse small intestine. These data indicate that MYO5B is responsible for the delivery of IMAC components to the apical membrane.NEW & NOTEWORTHY The intestinal epithelium absorbs nutrients and water through an elaborate apical membrane of highly organized microvilli. Microvilli organization is regulated by the intermicrovillar adhesion complexes, which create links between neighboring microvilli and control microvilli packing and density. In this study, we report a new trafficking partner of the IMAC, Myosin 5b. Loss of Myosin 5b results in a disorganized brush border and failure of IMAC proteins to reach the distal tips of microvilli.

Dataset Information

Commensal bacterial endocytosis in epithelial cells is dependent on myosin light chain kinase-activated brush border fanning by interferon-?.

Publications

Commensal bacterial endocytosis in epithelial cells is dependent on myosin light chain kinase-activated brush border fanning by interferon-γ.

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